1 82 J. DUESBERG. 



We come now to the description of a most interesting condition 

 in these interstitial cells of the opossum, a condition which I 

 noted first in preparations stained and fixed after Benda, where 

 it is most conspicuous. It can be seen also, however, in other 

 preparations, such as Flemming's, Meves', Hermann's and 

 Bouin's. A substance, which sometimes appears granular, at 

 other times amorphous, fills the intercellular spaces. Its quan- 

 tity is variable; some interspaces show so little of it as to escape 

 notice, others are widely dilated by the presence of large quanti- 

 ties of the substance, as shown in Fig. 13. It is most conspicuous 

 in preparations made after Benda's method because it takes up 

 avidly the crystal-violet, in striking contrast to the light-brown 

 color of the background and of the nuclei. The same substance 

 stains intensely with safranin and iron-hematoxylin; in the 

 Mallory method it takes up the orange and is consequently 

 rather inconspicuous. 



A closer investigation shows that from these intercellular 

 spaces processes penetrate into the cell-body (Figs. 12 and 13). 

 While most of these processes look like the substance accumu- 

 lated in the intercellular spaces, some have the sharp appearance 

 of a more definite structure, such as laminae of some sort, and 

 my first supposition was that I had to do with processes of con- 

 nective tissue penetrating into the cell-body, such as have been 

 described for large nerve-cells. A study of preparations stained 

 especially for the connective tissue failed, however, to substan- 

 tiate this opinion. After Mallory's stain, for instance, I could 

 not find any such process electively stained in blue. While the 

 thinnest fibrils of connective tissue in the sheath of the vessels 

 and the connective membrane of the seminiferous tubules gave 

 a typical collagenous reaction, in the same preparations the 

 intracellular processes always were stained in orange like the 

 intercellular substance. As a matter of fact, the study of these 

 preparations corroborates Lenhossek's description (p. 78). The 

 interstitial cells lie in heaps or irregular rows separated by the 

 larger vessels. It is quite exceptional to see a process of the 

 connective sheath of these vessels penetrate into a group of 

 interstitial cells. The cells are, as a rule, separated only by 

 intercellular spaces, virtual or real, and perhaps also in certain 



